This invention relates to squalene synthetase inhibitors, pharmaceutical compositions containing such inhibitors and the use of such inhibitors to treat hypercholesterolemia, hypertriglyceridemia, atherosclerosis, fungal infections, acne and Alzheimer's disease in mammals, including humans.
Plasma cholesterol levels have been positively correlated with the incidence of clinical events associated with coronary heart disease (CHD). Thus, pharmacological interventions that reduce cholesterol levels in mammals have a beneficial effect on CHD. In particular, decreased plasma low density lipoprotein (LDL) cholesterol levels are associated with decreased atherosclerosis and a decreased risk of CHD, and hypolipidemic agents used in either monotherapy or combination therapy are effective at reducing plasma LDL cholesterol levels and the subsequent risk of CHD.
Cholesterol metabolism in mammals involves a series of pathways including cholesterol absorption in the small intestine, cholesterol biosynthesis in numerous tissues (primarily the liver and small intestine), bile acid biosynthesis in the liver and reabsorption in the small intestine, synthesis of cholesterol-containing plasma lipoproteins by the liver and intestine, catabolism of the cholesterol-containing plasma lipoproteins by the liver and extrahepatic tissues and secretion of cholesterol and bile acids by the liver.
Cholesterol synthesis occurs in multiple tissues, but principally in the liver and the intestine. It is a multistep process starting from acetyl-coenzyme A catalyzed by a series of enzymes including hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase, HMG-CoA synthase, squalene synthetase, squalene epoxidase, squalene cyclase and lanosterol demethylase. Inhibition of catalysis by these enzymes or blocking HMG-CoA reductase gene expression is recognized as an effective means to reduce cholesterol biosynthesis (thus inhibitors thereof are referred to as cholesterol synthesis inhibitors) and can lead to a reduction in cholesterol levels. For example, there are known HMG-CoA reductase inhibitors (e.g., lovastatin, simvastatin, pravastatin, fluvastatin, atorvastatin, rivastatin, cerivastatin, nisvastatin) that are used for the treatment of hypercholesterolemia.
In fungi, the principal sterol is ergosterol, which is synthesized by a similar multi-step process to cholesterol. Inhibition of catalysis by these enzymes is recognized as an effective means of preventing fungal growth, both in vitro and in vivo. For example, there are known inhibitors of lamosterol demethylase (e.g., fluconazole, voriconazole, ketoconazole, itraconazole) and squalene epoxidase (e.g., terbinafine, naftifine, butenafine) which are used for the treatment of fungal infections.
Recently adopted National Cholesterol Education Program guidelines recommend aggressive lipid-lowering therapy for patients with pre-existing cardiovascular disease or for those with multiple factors that place them at increased risk.
The term squalene synthetase inhibitor refers to compounds that inhibit the condensation of 2 molecules of farnesylpyrophosphate to form squalene, a reaction that is catalyzed by the enzyme squalene synthetase. Such inhibition is readily determined by those skilled in the art according to standard assays (Meth. Enzymol. 1969; 15: 393-454 and Meth. Enzymol. 1985; 110:359-373 and references contained therein). A summary of squalene synthetase inhibitors has been compiled (Current Pharmaceutical Design 1996, 1, 1-40). European patent publication 0 567 026 A1 discloses certain 4,1-benzoxazepine derivatives as squalene synthase inhibitors and their use in the treatment of hypercholesterolemia and as fungicides. European patent publication 0 645 378 A1 discloses certain condensed seven- or eight-membered heterocycles as squalene synthetase inhibitors and their use in treatment and prevention of hypercholesterolemia and fungal infections. European patent publication 0 645 377 A1 discloses certain benzoxazepine derivatives as squalene synthetase inhibitors useful for the treatment of hypercholesterolemia or coronary sclerosis. European patent publication 0 611 749 A1 discloses certain substituted amic acid derivatives useful for treatment of arteriosclerosis. European patent publication 0705607 A2 discloses certain condensed seven- or eight-membered heterocyclic compounds useful as antihypertriglyceridemic agents. PCT Publication WO 96/09827 discloses certain combinations of cholesterol absorption inhibitors and cholesterol synthesis inhibitors including benzoxazepin derivatives and benzothiazepinone derivatives. European patent publication 0710725 A1 discloses a process for producing certain optically active compounds, including benzoxazepine compounds, having plasma cholesterol and triglyceride lowering activities.
Thus, although there are a variety of hypercholesterolemia therapies, there is a continuing need and a continuing search in this field of art for alternative therapies.